Mixotroph

Organisms may employ mixotrophy obligately or facultatively. • Obligate mixotrophy: To support growth and maintenance, an organism must utilize both heterotrophic and autotrophic means. • Obligate autotrophy with facultative heterotrophy: Autotrophy alone is sufficient for growth and maintenance, but heterotrophy may be used as a supplementary strategy when autotrophic energy is not enough, for example, when light intensity is low. • Facultative autotrophy with obligate heterotrophy: Heterotrophy is sufficient for growth and maintenance, but autotrophy may be used to supplement, for example, when prey availability is very low. • Facultative mixotrophy: Maintenance and growth may be obtained by heterotrophic or autotrophic means alone, and mixotrophy is used only when necessary. == Plants ==

Amongst plants, mixotrophy classically applies to carnivorous, hemi-parasitic and myco-heterotrophic species. However, this characterisation as mixotrophic could be extended to a higher number of clades as research demonstrates that organic forms of nitrogen and phosphorus—such as DNA, proteins, amino-acids or carbohydrates—are also part of the nutrient supplies of a number of plant species. Mycoheterotrophic plants form symbiotic relationships with mycorrhizal fungi, which provide them with organic carbon and nutrients from nearby photosynthetic plants or soil. They often lack chlorophyll or have reduced photosynthetic capacity. An example is Indian pipe, a white, non-photosynthetic plant that relies heavily on fungal networks for nutrients. Pinesap also taps into fungal networks for sustenance, similar to Indian pipe. Certain orchids, such as Corallorhiza, depend on fungi for carbon and nutrients while developing photosynthetic capabilities (especially in their early stages). '', bending in response to the trapping of an insect Carnivorous plants are plants that derive some or most of their nutrients from trapping and consuming animals or protozoans, typically insects and other arthropods, and occasionally small mammals and birds. They have adapted to grow in waterlogged sunny places where the soil is thin or poor in nutrients, especially nitrogen, such as acidic bogs. == Animals ==

Mixotrophy is less common among animals than among plants and microbes, but there are many examples of mixotrophic invertebrates and at least one example of a mixotrophic vertebrate. • The spotted salamander, Ambystoma maculatum, also hosts microalgae within its cells. Its embryos have been found to have symbiotic algae living inside them, the only known example of vertebrate cells hosting an endosymbiont microbe (unless mitochondria is considered). • Zoochlorella is a nomen rejiciendum for a genus of green algae assigned to Chlorella. The term zoochlorella (plural zoochlorellae) is sometimes used to refer to any green algae that lives symbiotically within the body of a freshwater or marine invertebrate or protozoan. • Reef-building corals (Scleractinia), like many other cnidarians (e.g. jellyfish, anemones), host endosymbiotic microalgae within their cells, thus making them mixotrophs. • The Oriental hornet, Vespa orientalis, can obtain energy from sunlight absorbed by its cuticle. It thus contrasts with the other animals listed here, which are mixotrophic with the help of endosymbionts. • The Leaf sheep, Costasiella kuroshimae, retains chloroplasts from algae it consumes so it can supplement its diet with photosynthesis via kleptoplasty Zooxanthellae.jpg|Zooxanthellae is a photosynthetic algae that lives inside hosts like coral. Anthopleura xanthogrammica 1.jpg|Anthopleura xanthogrammica gains its green colour from Zoochlorella. Mastigias papua.webmhd.webm|The spotted jelly, a mixotrophic jellyfish, lives in trophic mutualism with zooxanthella, a unicellular organism capable of photosynthesis. == Microorganisms ==

Bacteria and archaea • Paracoccus pantotrophus is a bacterium that can live chemoorganoheterotrophically, whereby many organic compounds can be metabolized. Also, a facultative chemolithoautotrophic metabolism is possible, as seen in colorless sulfur bacteria (some Thiobacillus), whereby sulfur compounds such as hydrogen sulfide, elemental sulfur, or thiosulfate are oxidized to sulfate. The sulfur compounds serve as electron donors and are consumed to produce ATP. The carbon source for these organisms can be carbon dioxide (autotrophy) or organic carbon (heterotrophy).Organoheterotrophy can occur under aerobic or under anaerobic conditions; lithoautotrophy takes place aerobically. Classifying protists radiolarian hosts Phaeocystis symbionts. File:Ecomare - schuimalg strand (7037-schuimalg-phaeocystis-ogb).jpg|White Phaeocystis algal foam washing up on a beach File:Paramecium bursaria.jpg|A single-celled ciliate with green zoochlorellae living inside endosymbiotically File:Euglena mutabilis - 400x - 1 (10388739803) (cropped).jpg| Euglena mutabilis, a photosynthetic flagellate File:Euglenoid movement.jpg|Euglenoid File:Acantharia confocal micrograph 2.png| Fluorescent micrograph of an acantharian with Phaeocystis symbionts fluorescing red (chlorophyll) ==Marine food webs==

Mixotrophs are especially common in marine environments, where the levels of energy from the sun and nutrients in the water can vary greatly. For example, in nutrient-poor (oligotrophic) waters, mixotrophic phytoplankton supplement their diet by consuming bacteria. The effects of mixotrophy on organic and inorganic carbon pools introduce a metabolic plasticity which blurs the lines between producers and consumers. Prior to the discovery of mixotrophs, it was thought that only organisms with chloroplasts were capable of photosynthesis and vice versa. This additional functional group of plankton, capable of both phototrophy and phagotrophy, provides a further boost in the biomass and energy transfer to higher trophic levels. s; MCIL, Mixotrophic ciliates; HNF, Heterotrophic nanoflagellates; DOC, Dissolved organic carbon; HDIN, Heterotrophic dinoflagellates. == See also ==